Pyrogenic emissions

Pyrogenic and natural biogenic emissions to the atmosphere in the Amazon basin may have an impact on the global tropospheric chemistry, because this region exhibits intense convective activity that injects gases and aerosols to high altitudes where they can be transported over long distances (Andreae et al. 1996, 1998, Echalar et al. 1998). Elemental concentrations in aerosols from Amazonia and Africa are very similar (Artaxo... 

Scholes, M., and M. O. Andreae. 2000. Biogenic and pyrogenic emissions from Africa and their impaa on the global atmosphere. Ambio 29 23-29. 

The main problem of styrene is high emission, which restricts applications in closed compartments (e.g., naval application). Styrene emission is a health hazard (threshold value of 50 ppm). The need to rednce the volatile organic compound (VOC) is not only expressed in government regulations, but also equally and persuasively by various environmental concerns. The evaporation of styrene can be reduced by the addition of waxes or pyrogenic silicic acid with hydrophilic and hydrophobic end groups. However, such additives may affect the interfacial properties of composites made out of polyester resins. Some styrene-less UPE resin formulations using diacrylate monomers have been reported [71]. However, mostly styrene is used as a reactive diluent in UPE resins. 

The U.S. EPA and others have used atmospheric lead emission factors to estimate lead entry to air in more recent years. An emission factor is a mathematical constant which links estimates for volumes of lead production or amounts of feed stocks to amoimts of lead exiting the air lead waste stream as a complex function of type of feed material and the engineering characteristics of lead metallurgical and other pyrogenic processes, such as municipal and other waste combustion. 

Besides some of the technical complexities noted above, air Pb at toxic levels for human exposures is at microlevel and submicrolevel amounts. A brief reading of the levels of air Pb permissible in emissions to the human environment makes this apparent. This analytical reality meant that quantitative analysis of air Pb for purposes of health risk characterization and evaluation of dose—response relationships was not feasible. Second, the fact that lead entered ambient air where people live by either mobile (largely vehicular emissions) or point sources (e.g., smelters, incinerators, other pyrogenic sources) meant legislation and associated rales and regulations had to be crafted with these sources in mind. 

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